Umar Jameer Lyles

A 330nA energy-harvesting charger with battery management for solar and thermoelectric energy harvesting

Harvesting energy from ambient energy sources such as solar and thermal gradients is one solution to address the dramatic increase in energy consumption of personal electronics. In this paper, an ultra low quiescent current charger and battery management IC that can efficiently extract energy from solar panels and thermoelectric generators to charge batteries and super capacitors is presented. While previous works on energy harvesting [1-5] report efficient DC-DC converters to extract the energy from the harvester, not all of them provide complete battery management functionality for various chemistries. Also, maximum power point tracking (MPPT) which is critical in energy harvesting applications is not provided in some of the published work. In this paper, a charger and battery management IC with 330nA quiescent current is presented. The IC can cold start from 330mV and 5μW of input power. The charger achieves efficiency greater than 80% at single cell solar voltages of 0.5V. A low quiescent current battery management architecture involving sampled circuits, sub regulated rails and clock gating is demonstrated.

A Bandpass ΔΣ DDFS-Driven 19GHz Frequency Synthesizer for FMCW Automotive Radar

A 19GHz frequency-modulated continuous-wave TX based on a bandpass ΔΣ DDFS-driven RF frequency synthesizer is presented. Implemented in a 0.25μm SiGe process, the synthesizer draws 63mA from a 2.5V supply while achieving a 512MHz FM deviation with a 200Hz FM rate at a center frequency of 19GHz. The measured phase noise of the frequency synthesizer is -113.68dBc/Hz at 1MHz offset frequency from a 19GHz carrier

A low power bandpass /spl Sigma/ /spl Delta/ modulator injection locked synthesizer

A fully integrated 0.13-mum CMOS RFIC PLL transmitter for GFSK/GMSK modulation at 2.4-GHz ISM band is presented. A bandpass SigmaDelta direct digital frequency synthesized (BPSADDFS) reference oscillator is developed to provide a wideband RF PLL with a frequency modulated signal. The RF PLL-transmitter uses a single-bit bandpass SigmaDelta modulated injection locked oscillator as a reference signal. The measurement results show that the transmitter achieves a 0-dBm output power at 1-Mbit/sec data-rate when using a 0.5BT GFSK modulation. The ring oscillator VCO has a measured phase noise of -104dBc/Hz at 1-MHz offset from the RF carrier at 2.4GHz. The digital transmitter complies with Bluetooth Class 3 requirements and occupies 1.73mm2 silicon area